This document summarizes a study on the quality control of concrete production in Dhaka City, Bangladesh. The study investigated the existing practices through a survey of 45 construction sites. The survey found that most concrete production companies in Dhaka City are neither aware of key quality control factors nor following quality control procedures. As a result, inferior quality concrete is being produced that can affect the strength and durability of structures. The document discusses factors that affect concrete quality including materials, personnel, equipment, workmanship in batching, mixing, transporting, placing, compacting, curing and testing of concrete.
IRJET-Permeable Concrete as a Road PavementIRJET Journal
This document discusses permeable concrete as a potential pavement material. Permeable concrete contains voids that allow water to drain through it, addressing issues like waterlogging. It can reduce costs by eliminating needs for drainage systems. The document reviews studies on permeable concrete properties like strength and permeability. Mix designs are presented and tested, with a 4.5:1:0.4 aggregate-cement-water ratio found to produce the highest strength. Permeable concrete is found to be suitable for low-traffic rural roads but lacks strength for high-traffic areas. It has benefits like groundwater recharge if implemented but requires more study.
The notable demand for the want of cement in our time has stimulated increment in cement production and increment in manufacturers to be had in our day. These in turn amongst others have brought about failure of buildings and other construction members. As a result, the need to ensure the quality of available cement in circulation is of utmost paramount. This research work studies the available Portland lime cement of grade 42.5 only, in Nigeria from such company as company A, company B, and company C. The qualities and properties of the Portland lime cement from every of the above-named companies were investigated and as compared. Properties like Fineness, Setting Time, Chemical composition, Specific gravity, Consistency, Loss of ignition, Strength (compressive strength, and flexural strength), Micro structural analysis were determined according to relevant BS EN 197-1 (2011) and (ASTMC) 150-92 standards. These tests were carried out with the usage of scanning electron microscope, X-ray fluorescence spectrometer, Vicat apparatus, compressive strength machine, consistency apparatus and Chatelier flask, among others. The results showed that the chemical composition mostly of CaO, SiO2, AL2O3 and MgO in the cement +are within the acceptable limit of 60.0-67.0, 17.0-25.0, 3.0-8.0 and 0.1-4.0 respectively in the BS 4550: Part 3 (1979). The results of the compressive strength acquired for all the cement have been a way beneath the standardized result expected for grade 42.5. These could partly be traced to the cement micro-structure as Company C with the best morphology exhibits better compressive strength than others. Improvement on the cement morphology by the manufacturers could lead to compressive strength improvement. It was also discovered that one of the important factors that would have contributed to the low compressive strength was excessive amount of silt/clay content material inside the sand used.
IRJET- Critical Analysis of Properties of Ready Mix Concrete with Site Mix...IRJET Journal
This document analyzes and compares the properties of ready mix concrete (RMC) and site mixed concrete (also called hand mixed concrete or in-situ concrete) used in the construction of a smart road project in Bhopal, India. The study tested the workability and compressive strength of different grades of concrete from RMC and site mixing. The results were analyzed to determine any deviations between the two concretes and ensure the quality of concrete used met standards. The properties of materials used - cement, fine aggregate, coarse aggregate - were also examined. The methodology of the study involved testing ingredients, designing mixes, preparing and curing samples, and analyzing test results to draw conclusions.
IRJET- Utilization of Glass Fibers in Concrete: A ReviewIRJET Journal
The document reviews research on utilizing glass fibers in concrete to improve its mechanical properties and durability. Several studies are summarized that tested adding different percentages of glass fibers from 0-1.6% by weight of cement to concrete mixtures. The results showed improvements in properties like compressive strength, flexural strength, tensile strength, and resistance to cracking, corrosion, and fire. Specifically, adding 1.2% glass fibers increased compressive strength by 17.36% and flexural strength by 35% compared to plain concrete. The review concludes that incorporating small amounts of glass fibers is an effective way to enhance the performance of concrete.
IRJET- A Review Paper on Experimental Investigation of Crumb Rubber ConcreteIRJET Journal
The document reviews previous experimental work on crumb rubber concrete. It summarizes several studies that investigated replacing natural aggregates or mixtures with crumb rubber. The studies found that compressive strength generally decreased as crumb rubber content increased but durability properties like resistance to freezing/thawing and sulfate attack improved. Some studies found that pretreating the crumb rubber with chemicals or coatings could minimize strength reductions. Replacing up to 20% of fine aggregates or 5% of total mixtures with crumb rubber produced acceptable strength properties for some applications while improving sustainability by using waste tire material.
IRJET- Evaluation of Strength Characteristics of Triple Blended Concrete usin...IRJET Journal
This document presents the results of a study that evaluated the strength and durability properties of concrete with a triple blend of cement, fly ash, and ground granulated blast furnace slag (GGBS). Several mix designs were tested with varying replacement levels of cement with GGBS and fly ash. The mixes were tested for workability, compressive strength, tensile strength, permeability, and modulus of elasticity. The results showed that mixes with 30% GGBS and 15% fly ash and 35% GGBS and 15% fly ash exhibited the highest compressive and tensile strengths. Permeability was lowest in mixes with higher fly ash content. Using a triple blend of cement, fly ash, and GGB
IRJET - - Experimental Study on the Behavior of Concrete by using Jute Fiber ...IRJET Journal
This document presents the results of an experimental study on the effects of replacing cement with ground granulated blast furnace slag (GGBS) and adding jute fiber to concrete. Concrete cubes and cylinders were made by replacing cement with GGBS in amounts ranging from 0-55% and adding jute fiber in amounts ranging from 0-0.6%. The slump, compressive strength, tensile strength, and flexural strength of the concrete mixtures were tested at curing periods of 7, 14, and 28 days. The test results showed that replacing cement with GGBS up to 45% and adding 0.45% jute fiber increased the compressive strength of the concrete. Additionally, the addition of jute
IRJET- Effect of Bakelite Plastic Admixture as a Coarse Aggregate in a Concre...IRJET Journal
This document summarizes a study on the effect of using bakelite plastic as a partial replacement for coarse aggregate in concrete. The researchers prepared concrete mixes with 5%, 10%, 15%, and 20% replacements of coarse aggregate with bakelite plastic. They found that compressive strength decreased with higher bakelite content, while tensile strength increased with higher bakelite content. The study concluded that a 20% replacement of coarse aggregate provided the maximum tensile strength of concrete at 28 days, demonstrating that bakelite plastic can improve some properties of concrete when used as a partial aggregate replacement.
IRJET-Permeable Concrete as a Road PavementIRJET Journal
This document discusses permeable concrete as a potential pavement material. Permeable concrete contains voids that allow water to drain through it, addressing issues like waterlogging. It can reduce costs by eliminating needs for drainage systems. The document reviews studies on permeable concrete properties like strength and permeability. Mix designs are presented and tested, with a 4.5:1:0.4 aggregate-cement-water ratio found to produce the highest strength. Permeable concrete is found to be suitable for low-traffic rural roads but lacks strength for high-traffic areas. It has benefits like groundwater recharge if implemented but requires more study.
The notable demand for the want of cement in our time has stimulated increment in cement production and increment in manufacturers to be had in our day. These in turn amongst others have brought about failure of buildings and other construction members. As a result, the need to ensure the quality of available cement in circulation is of utmost paramount. This research work studies the available Portland lime cement of grade 42.5 only, in Nigeria from such company as company A, company B, and company C. The qualities and properties of the Portland lime cement from every of the above-named companies were investigated and as compared. Properties like Fineness, Setting Time, Chemical composition, Specific gravity, Consistency, Loss of ignition, Strength (compressive strength, and flexural strength), Micro structural analysis were determined according to relevant BS EN 197-1 (2011) and (ASTMC) 150-92 standards. These tests were carried out with the usage of scanning electron microscope, X-ray fluorescence spectrometer, Vicat apparatus, compressive strength machine, consistency apparatus and Chatelier flask, among others. The results showed that the chemical composition mostly of CaO, SiO2, AL2O3 and MgO in the cement +are within the acceptable limit of 60.0-67.0, 17.0-25.0, 3.0-8.0 and 0.1-4.0 respectively in the BS 4550: Part 3 (1979). The results of the compressive strength acquired for all the cement have been a way beneath the standardized result expected for grade 42.5. These could partly be traced to the cement micro-structure as Company C with the best morphology exhibits better compressive strength than others. Improvement on the cement morphology by the manufacturers could lead to compressive strength improvement. It was also discovered that one of the important factors that would have contributed to the low compressive strength was excessive amount of silt/clay content material inside the sand used.
IRJET- Critical Analysis of Properties of Ready Mix Concrete with Site Mix...IRJET Journal
This document analyzes and compares the properties of ready mix concrete (RMC) and site mixed concrete (also called hand mixed concrete or in-situ concrete) used in the construction of a smart road project in Bhopal, India. The study tested the workability and compressive strength of different grades of concrete from RMC and site mixing. The results were analyzed to determine any deviations between the two concretes and ensure the quality of concrete used met standards. The properties of materials used - cement, fine aggregate, coarse aggregate - were also examined. The methodology of the study involved testing ingredients, designing mixes, preparing and curing samples, and analyzing test results to draw conclusions.
IRJET- Utilization of Glass Fibers in Concrete: A ReviewIRJET Journal
The document reviews research on utilizing glass fibers in concrete to improve its mechanical properties and durability. Several studies are summarized that tested adding different percentages of glass fibers from 0-1.6% by weight of cement to concrete mixtures. The results showed improvements in properties like compressive strength, flexural strength, tensile strength, and resistance to cracking, corrosion, and fire. Specifically, adding 1.2% glass fibers increased compressive strength by 17.36% and flexural strength by 35% compared to plain concrete. The review concludes that incorporating small amounts of glass fibers is an effective way to enhance the performance of concrete.
IRJET- A Review Paper on Experimental Investigation of Crumb Rubber ConcreteIRJET Journal
The document reviews previous experimental work on crumb rubber concrete. It summarizes several studies that investigated replacing natural aggregates or mixtures with crumb rubber. The studies found that compressive strength generally decreased as crumb rubber content increased but durability properties like resistance to freezing/thawing and sulfate attack improved. Some studies found that pretreating the crumb rubber with chemicals or coatings could minimize strength reductions. Replacing up to 20% of fine aggregates or 5% of total mixtures with crumb rubber produced acceptable strength properties for some applications while improving sustainability by using waste tire material.
IRJET- Evaluation of Strength Characteristics of Triple Blended Concrete usin...IRJET Journal
This document presents the results of a study that evaluated the strength and durability properties of concrete with a triple blend of cement, fly ash, and ground granulated blast furnace slag (GGBS). Several mix designs were tested with varying replacement levels of cement with GGBS and fly ash. The mixes were tested for workability, compressive strength, tensile strength, permeability, and modulus of elasticity. The results showed that mixes with 30% GGBS and 15% fly ash and 35% GGBS and 15% fly ash exhibited the highest compressive and tensile strengths. Permeability was lowest in mixes with higher fly ash content. Using a triple blend of cement, fly ash, and GGB
IRJET - - Experimental Study on the Behavior of Concrete by using Jute Fiber ...IRJET Journal
This document presents the results of an experimental study on the effects of replacing cement with ground granulated blast furnace slag (GGBS) and adding jute fiber to concrete. Concrete cubes and cylinders were made by replacing cement with GGBS in amounts ranging from 0-55% and adding jute fiber in amounts ranging from 0-0.6%. The slump, compressive strength, tensile strength, and flexural strength of the concrete mixtures were tested at curing periods of 7, 14, and 28 days. The test results showed that replacing cement with GGBS up to 45% and adding 0.45% jute fiber increased the compressive strength of the concrete. Additionally, the addition of jute
IRJET- Effect of Bakelite Plastic Admixture as a Coarse Aggregate in a Concre...IRJET Journal
This document summarizes a study on the effect of using bakelite plastic as a partial replacement for coarse aggregate in concrete. The researchers prepared concrete mixes with 5%, 10%, 15%, and 20% replacements of coarse aggregate with bakelite plastic. They found that compressive strength decreased with higher bakelite content, while tensile strength increased with higher bakelite content. The study concluded that a 20% replacement of coarse aggregate provided the maximum tensile strength of concrete at 28 days, demonstrating that bakelite plastic can improve some properties of concrete when used as a partial aggregate replacement.
An Experimental Study on Properties of Concrete using Waste Plastic Scrap Mat...ijtsrd
Investigations were done on M 30grade concrete by replacing coarse aggregate partially by plastic fiber to get maximum strength. This work presents the Strength and workability results of waste plastic fiber reinforced concrete WPFRC . The different percentages of waste plastic fiber reinforced concrete used in the experimentation are 0 , 0.5 , 1 , and 2 by partial replacement of coarse aggregate using plastic fiber This Study presents the satisfactory results on various strength tests of concrete containing plastic fiber as a partial replacement of coarse aggregate and would help to resolve solid waste disposal problem. However, further research work is still necessary in order to have a more in depth understanding. Mahendra Yadav | Pratiksha Malviya ""An Experimental Study on Properties of Concrete using Waste Plastic Scrap Materials as Partial Replacement of Coarse Aggregate"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25195.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/25195/an-experimental-study-on-properties-of-concrete-using-waste-plastic-scrap-materials-as-partial-replacement-of-coarse-aggregate/mahendra-yadav
Critical Literature Review on Improvement of Concrete Properties by Bacterial...IRJET Journal
This document provides a literature review of research on improving concrete properties using bacterial solutions. It summarizes 15 previous studies that investigated how adding various bacteria like Bacillus pasteurii and Bacillus subtilis to concrete affects mechanical properties and durability. The studies found that bacterial concrete has higher compressive strength, flexural strength, elastic modulus, and lower water absorption and permeability compared to normal concrete. The bacteria are able to precipitate calcium carbonate in concrete cracks, potentially providing a self-healing effect. Bacterial solutions from 105-107 cells/ml were found to be most effective. Using fly ash or slag cement along with bacterial solutions can further enhance concrete properties. Overall, the literature demonstrates that bacterial solutions have potential to
Experimental Investigation on Durability Properties of Self Compacting Concre...IRJET Journal
The document discusses experimental investigation on the durability properties of self-compacting concrete by partially replacing fly ash and ground granulated blast furnace slag (GGBS). It provides background on self-compacting concrete and discusses guidelines and specifications for acceptance criteria. It then reviews several previous studies that investigated replacing natural aggregates or cement with recycled materials and assessed fresh and hardened concrete properties. The literature review found that replacement of up to 30% aggregates or cement resulted in only minor decreases in compressive strength while improving sustainability.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IRJET- Investigations on the Durability Parameters of Different Grades of...IRJET Journal
This document investigates the durability parameters of different grades of concrete. It studies parameters like water absorption, water absorptivity, oxygen permeability, and chloride permeability. The study aims to evaluate the effect of water-to-cement ratio and cement content on durability indices. It prepares different concrete mixtures with varying water-to-cement ratios (0.35, 0.5, 0.65) and cement contents (300, 350, 400 kg/m3) and tests them for compressive strength and various durability parameters. The results show that lower water-to-cement ratios and higher cement contents provide higher compressive strength and improved durability as measured by durability test indices. However, the
Applications and Effects of Silica Fume and Nano Silica on the Compressive St...ijtsrd
The application of nanotechnology in concrete adds new content to efforts to improve its performance. Due to the very small size of nanomaterials, the properties of concrete can be influenced by changing the microstructure. The study involved the use of 215 nm nano silica to increase the compressive strength of concrete. Experimental studies were performed at 0.4 , 0.7 and 1 of BC. These tests have greatly improved the strength of the early pressure and the overall pressure strength of the concrete. As the percentage of nano silica increases, an increase in strength is observed. Concrete is the material of present and future. Its widespread use in structures, from buildings to factories, bridges and airports, makes it one of the most searched materials in the 21st century. Due to rapid population explosion and the rise of technology to meet these needs, there is an urgent need to improve the strength and durability of concrete. Among the various materials used in concrete production, cement plays an important role due to its size and adhesive properties. Therefore, for the production of improved concrete, the cement humidification mechanism should be studied properly and better alternatives should be proposed. Current research is the design of M40 M30 quality of concrete. The mixtures developed to obtain more rheological properties and solid properties were studied. In this study, the cement is replaced by silica smoke and nano silica materials. In addition, it is planned to determine the number of predictions of cubes in the program. The current design of the probe is the strength of M40 and M30 quality of concrete. This thesis explore the standard optimization ratio for silica and fume to get the best compressive strength. Further this has to check for Indian standard uses for developing the demand of quality users in India. Finally this research lead us to create the console for evaluating the strength of concrete. Syed Basharat Andrabi | Er. Jagdeep Singh ""Applications and Effects of Silica Fume and Nano Silica on the Compressive Strength of Concrete"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25069.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/25069/applications-and-effects-of-silica-fume-and-nano-silica-on-the-compressive-strength-of-concrete/syed-basharat-andrabi
IRJET- Functionally Graded Concrete: An Experimental AnalysisIRJET Journal
This document summarizes an experimental analysis of functionally graded concrete. Functionally graded concrete consists of concrete with varying material properties or compositions across its structure to optimize performance. The study investigated concrete mixtures with partial cement replacement using dolomite powder. Specimens including cubes, cylinders, and beams were cast with normal concrete in the compression zone and concrete with 20-40% dolomite-replaced cement in the tension zone. Testing showed that mixtures with 30% dolomite replacement and an interface at 75mm from the bottom achieved the highest compressive strength. Flexural strength was also highest for mixtures with a graded interface. The results indicate that functionally graded concrete is a promising alternative to conventional concrete.
IRJET-Effect of Aggregate Flakiness on the Compressive Strength and Workabili...IRJET Journal
This document summarizes a study that will investigate the effect of flaky aggregate percentage (ranging from 20-70%) on the compressive strength and workability of concrete. 36 concrete cubes will be cast with varying flaky aggregate content and a water-cement ratio of 0.5. The cubes will be tested for compressive strength at 7 and 28 days. Previous studies have found that flaky aggregates increase voids and reduce strength and workability beyond a certain limit. It is expected that compressive strength will decrease as flaky aggregate percentage increases due to more voids, and that workability will also decrease with higher flaky content.
IRJET- Analysis of Compressive Strength of Self Curing Concrete Made using Po...IRJET Journal
This document analyzes the compressive strength of self-curing concrete made using Polyethylene Glycol (PEG400). PEG400 is used as an internal curing compound to prevent moisture loss from concrete and allow for more complete hydration. Tests were conducted on M20 grade concrete with 0-1.5% PEG400 by weight of cement. Results found that 0.5-1% PEG400 concrete had higher 7 and 28-day compressive strengths than plain concrete, with less cracking. PEG400 improved workability and water retention, allowing for better strength development over time compared to traditional curing methods.
IRJET- A Review on Strength Properties of Concrete with Partial Replacement o...IRJET Journal
This document summarizes research on the strength properties of concrete with partial replacement of cement by ground granulated blast furnace slag (GGBS). It first provides background on GGBS, noting that it is a byproduct of iron manufacturing with similar chemical composition to portland cement. The document then reviews literature on the topic, finding that compressive strength of GGBS concrete increased at 40% replacement but decreased with further additions. Experimental results from the study found optimal GGBS replacement is 40% for maximum strength. In conclusion, GGBS can improve concrete strength when used to partially replace cement.
IRJET- Study on Mechanical Propertiesof Polymer ConcreteIRJET Journal
This document summarizes a study on the mechanical properties of polymer concrete. Specifically, it examines how adding different polymers to concrete impacts properties like compressive strength, tensile strength, and workability. Concrete cubes and beams were produced using cement, aggregates, and various polymers like polyvinyl chloride, styrene butadiene rubber latex, polystyrene, and polypropylene. Tests on the samples found that adding 10% styrene butadiene rubber latex increased compressive and tensile strengths the most compared to other polymers and plain concrete. Workability was highest with 15% styrene butadiene rubber latex. The study concludes certain polymers like polyvinyl chloride and styrene butadiene rubber latex can improve
This document discusses a study that evaluated the economic benefits of using an activator material called A-BFS (Activator Blast Furnace Slag) in concrete mixes. The study found that using A-BFS can induce early strength in concrete containing blast furnace slag, potentially allowing construction cycles for reinforced concrete buildings to be reduced from 6-4 days. The study conducted physical property tests on concrete with partial replacement of ordinary Portland cement with A-BFS. It then estimated the potential construction cost savings from shortening construction periods for a sample apartment building project using different A-BFS mix ratios. The study estimated that Cases 3 and 4 could save around 106 million and 160 million Korean won, respectively, through an earlier removal
IRJET- A Review on Applicability of Bacteria in Self-Healing Self-Curing Conc...IRJET Journal
This document reviews the applicability of bacteria as self-healing agents in self-curing concrete. It discusses how various studies have encapsulated bacteria in concrete to induce calcium carbonate precipitation to heal cracks. The document also examines how chemicals like polyetheylene glycol have been used as internal curing agents to improve hydration and strength of self-curing concrete without external curing. The optimal dosages of these agents found in different studies are summarized. The document concludes that incorporating self-healing efficiency through bacterial precipitation and internal curing can significantly reduce maintenance costs for concrete structures.
IRJET-Effect of Mixed Fiber Reinforced Concrete Exposed to Different Exposure...IRJET Journal
This document summarizes a study on the effect of mixed fiber reinforced concrete exposed to different conditions. Cubic concrete specimens containing various combinations of steel and glass fibers were cast and exposed to either water or 5% sulfuric acid solutions. The specimens were tested after 7 and 28 days to evaluate properties like compressive strength, ultrasonic pulse velocity (UPV), and weight loss. The results showed that concrete with a 50% glass fiber and 50% steel fiber mixture performed best in terms of UPV values and compressive strength gain when exposed to both water and acid conditions. Specimens exposed to acid generally showed higher UPV and lower weight loss compared to those cured in water. The study aims to evaluate the durability of fiber
Experimental Investigation of High – Strength Characteristics of Self Curing ...IJMTST Journal
In concrete structures exposed to the ambient air at early ages, the moisture content in concrete
decreases due to moisture diffusion. In addition, self-desiccation due to hydration of cement causes an
additional decrease of moisture content in concrete at early ages, especially for high-strength concrete. In this
study, the internal relative humidity in drying concrete specimens was measured at early ages. Furthermore,
the variation of relative humidity due to self-desiccation in sealed specimen was measured. The moisture
distribution in low-strength concrete with high water/cement ratio was mostly influenced by moisture
diffusion due to drying rather than self-desiccation. In high-strength concrete with low water/cement ratio,
however, self-desiccation had a considerable influence on moisture distribution. The results obtained from
the moisture diffusion theory were in good agreement with experimental results.
IRJET- Crushed Plastic Waste in ConcreteIRJET Journal
This document presents a study on the use of crushed plastic waste as a partial replacement for coarse aggregate in concrete. Several concrete mixes were prepared with 10%, 20%, and 30% replacement of coarse aggregate with crushed plastic waste. The workability and compressive and flexural strengths of the concrete mixes were tested and compared to a control concrete mix without plastic waste. The results showed that concrete with 10% plastic waste replacement achieved a compressive strength similar to the control mix. Compressive and flexural strengths decreased with higher levels of plastic waste replacement but remained acceptable. The study concluded that crushed plastic waste can partially replace coarse aggregate in concrete, particularly at a 10% replacement level, providing a potential use for plastic waste while maintaining good concrete
IRJET- Rice Husk as a Filler Material in High Strength ConcreteIRJET Journal
This document discusses using rice husk ash (RHA) as a filler material in high-strength concrete to improve properties and reduce costs. RHA can replace 5-10% of cement through pozzolanic reactions that improve the cementation matrix and strength. Tests found compressive strengths of 30 MPa after 28 days for concrete with RHA replacements, similar to plain high-strength concrete. Using RHA promotes more sustainable use of agricultural byproducts in construction.
Comparative Analysis of Destructive and Non-Destructive Testing Method of Con...ijtsrd
This work presents a study on the comparison between Destructive Compressive test and Non destructive testing techniques Schmidt Rebound Hammer . Tests moisture content, Sieve analysis, particle density for aggregate and cement paste, bulk density, standard consistency of cement, slump test were performed on both the aggregate and cement to compare their accuracy of both methods and test the quality of the material to be used for concrete casting and estimating the strength of concrete. Seventy samples cubes of 150 x 150 x 150mm were prepared using mix designs of 1 2 4 with a constant w c ratio of 0.45 and were tested at 7, 14, 21 and 28 days respectively. From the results, the rebound number increased from an average of 12 for 7days to an average rebound number of 17.7 for 28days which is similar to the increment in compressive strength from an average of 24.3 for 7days to an average of 32 for 28days which show that the increment in the strength is uniform but 5 difference in value obtained. The slump test was between 62 78mm. From the results of the analysis, it was observed that the strength obtained from destructive process conformed to targeted mix value, whereas that of the Rebound hammer was below these values. Statistical analysis of the results obtained showed that 5 difference exists between the results obtained from the two methods. Hence, there was no significant difference between the means of the two methods for both mixes at a 0.05 level of significance. Non destructive Testing is observed to be more economical as it required no electricity and can also be used directly in the field. Onyeka, F. C | Mama, B. O "Comparative Analysis of Destructive and Non-Destructive Testing Method of Concrete Strength using Compressive and Rebound Harmmer Testing Method" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29389.pdfPaper URL: https://www.ijtsrd.com/engineering/civil-engineering/29389/comparative-analysis-of-destructive-and-non-destructive-testing-method-of-concrete-strength-using-compressive-and-rebound-harmmer-testing-method/onyeka-f-c
Impact of Biomedical Waste on City Environment :Case Study of Pune India.IOSR Journals
Indian cities are facing problem of Biomedical waste management in the wake of urban development. The number of healthcare facilities is increasing day by day resulting in large-scale generation of bio medical waste. It has been observed that inadequate disposal of biomedical waste is creating highly unhygienic environment and posing serious heath threat for inhabitants. Present paper discusses the issue of biomedical waste management from a wider perspective with special emphasis on chemical waste which is one of the most hazardous wastes in present context. Various types of biomedical waste with reference to generation, handling and disposal practices are presented. It includes study and analysis of the parameters which affect the quality of environment to explore their impact on city environments. The current practices of handling such waste is presented based on a study conducted in city of Pune, which is the second largest city in the state of Maharashtra, India. It is aimed to put forth the importance of adequate handling and treatment of biomedical waste with reference to healthy and hygienic living environment for inhabitants to live in.
Outlining Bangla Word Dictionary for Universal Networking LanguageIOSR Journals
This document discusses outlining a Bangla word dictionary for the Universal Networking Language (UNL) system. UNL is an artificial language that allows computers to process information across languages. The authors have been working to include Bangla in the UNL system. They describe the format of a UNL dictionary entry, which includes the headword (Bangla word), universal word, and grammatical attributes. Simply searching the UNL knowledge base for universal words is not effective, so they propose finding universal words based on existing translations of Bangla texts to English and their UNL expressions. The goal is to develop a Bangla dictionary to facilitate converting Bangla sentences to UNL format.
Flash chromatography guided fractionation and antibacterial activity studies ...IOSR Journals
This document summarizes a study that fractionated extracts of Angelica archangelica roots using flash chromatography and tested the fractions for antibacterial activity. Several fractions showed promising antibacterial activity, with minimum inhibitory concentrations ranging from 125-500 μg/ml against four bacterial strains. The most active fractions were from methanol extracts. All ethyl acetate fractions exhibited activity. Further investigation of these fractions could uncover bioactive compounds responsible for the plant's traditional medicinal uses.
An Experimental Study on Properties of Concrete using Waste Plastic Scrap Mat...ijtsrd
Investigations were done on M 30grade concrete by replacing coarse aggregate partially by plastic fiber to get maximum strength. This work presents the Strength and workability results of waste plastic fiber reinforced concrete WPFRC . The different percentages of waste plastic fiber reinforced concrete used in the experimentation are 0 , 0.5 , 1 , and 2 by partial replacement of coarse aggregate using plastic fiber This Study presents the satisfactory results on various strength tests of concrete containing plastic fiber as a partial replacement of coarse aggregate and would help to resolve solid waste disposal problem. However, further research work is still necessary in order to have a more in depth understanding. Mahendra Yadav | Pratiksha Malviya ""An Experimental Study on Properties of Concrete using Waste Plastic Scrap Materials as Partial Replacement of Coarse Aggregate"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25195.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/25195/an-experimental-study-on-properties-of-concrete-using-waste-plastic-scrap-materials-as-partial-replacement-of-coarse-aggregate/mahendra-yadav
Critical Literature Review on Improvement of Concrete Properties by Bacterial...IRJET Journal
This document provides a literature review of research on improving concrete properties using bacterial solutions. It summarizes 15 previous studies that investigated how adding various bacteria like Bacillus pasteurii and Bacillus subtilis to concrete affects mechanical properties and durability. The studies found that bacterial concrete has higher compressive strength, flexural strength, elastic modulus, and lower water absorption and permeability compared to normal concrete. The bacteria are able to precipitate calcium carbonate in concrete cracks, potentially providing a self-healing effect. Bacterial solutions from 105-107 cells/ml were found to be most effective. Using fly ash or slag cement along with bacterial solutions can further enhance concrete properties. Overall, the literature demonstrates that bacterial solutions have potential to
Experimental Investigation on Durability Properties of Self Compacting Concre...IRJET Journal
The document discusses experimental investigation on the durability properties of self-compacting concrete by partially replacing fly ash and ground granulated blast furnace slag (GGBS). It provides background on self-compacting concrete and discusses guidelines and specifications for acceptance criteria. It then reviews several previous studies that investigated replacing natural aggregates or cement with recycled materials and assessed fresh and hardened concrete properties. The literature review found that replacement of up to 30% aggregates or cement resulted in only minor decreases in compressive strength while improving sustainability.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IRJET- Investigations on the Durability Parameters of Different Grades of...IRJET Journal
This document investigates the durability parameters of different grades of concrete. It studies parameters like water absorption, water absorptivity, oxygen permeability, and chloride permeability. The study aims to evaluate the effect of water-to-cement ratio and cement content on durability indices. It prepares different concrete mixtures with varying water-to-cement ratios (0.35, 0.5, 0.65) and cement contents (300, 350, 400 kg/m3) and tests them for compressive strength and various durability parameters. The results show that lower water-to-cement ratios and higher cement contents provide higher compressive strength and improved durability as measured by durability test indices. However, the
Applications and Effects of Silica Fume and Nano Silica on the Compressive St...ijtsrd
The application of nanotechnology in concrete adds new content to efforts to improve its performance. Due to the very small size of nanomaterials, the properties of concrete can be influenced by changing the microstructure. The study involved the use of 215 nm nano silica to increase the compressive strength of concrete. Experimental studies were performed at 0.4 , 0.7 and 1 of BC. These tests have greatly improved the strength of the early pressure and the overall pressure strength of the concrete. As the percentage of nano silica increases, an increase in strength is observed. Concrete is the material of present and future. Its widespread use in structures, from buildings to factories, bridges and airports, makes it one of the most searched materials in the 21st century. Due to rapid population explosion and the rise of technology to meet these needs, there is an urgent need to improve the strength and durability of concrete. Among the various materials used in concrete production, cement plays an important role due to its size and adhesive properties. Therefore, for the production of improved concrete, the cement humidification mechanism should be studied properly and better alternatives should be proposed. Current research is the design of M40 M30 quality of concrete. The mixtures developed to obtain more rheological properties and solid properties were studied. In this study, the cement is replaced by silica smoke and nano silica materials. In addition, it is planned to determine the number of predictions of cubes in the program. The current design of the probe is the strength of M40 and M30 quality of concrete. This thesis explore the standard optimization ratio for silica and fume to get the best compressive strength. Further this has to check for Indian standard uses for developing the demand of quality users in India. Finally this research lead us to create the console for evaluating the strength of concrete. Syed Basharat Andrabi | Er. Jagdeep Singh ""Applications and Effects of Silica Fume and Nano Silica on the Compressive Strength of Concrete"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25069.pdf
Paper URL: https://www.ijtsrd.com/engineering/civil-engineering/25069/applications-and-effects-of-silica-fume-and-nano-silica-on-the-compressive-strength-of-concrete/syed-basharat-andrabi
IRJET- Functionally Graded Concrete: An Experimental AnalysisIRJET Journal
This document summarizes an experimental analysis of functionally graded concrete. Functionally graded concrete consists of concrete with varying material properties or compositions across its structure to optimize performance. The study investigated concrete mixtures with partial cement replacement using dolomite powder. Specimens including cubes, cylinders, and beams were cast with normal concrete in the compression zone and concrete with 20-40% dolomite-replaced cement in the tension zone. Testing showed that mixtures with 30% dolomite replacement and an interface at 75mm from the bottom achieved the highest compressive strength. Flexural strength was also highest for mixtures with a graded interface. The results indicate that functionally graded concrete is a promising alternative to conventional concrete.
IRJET-Effect of Aggregate Flakiness on the Compressive Strength and Workabili...IRJET Journal
This document summarizes a study that will investigate the effect of flaky aggregate percentage (ranging from 20-70%) on the compressive strength and workability of concrete. 36 concrete cubes will be cast with varying flaky aggregate content and a water-cement ratio of 0.5. The cubes will be tested for compressive strength at 7 and 28 days. Previous studies have found that flaky aggregates increase voids and reduce strength and workability beyond a certain limit. It is expected that compressive strength will decrease as flaky aggregate percentage increases due to more voids, and that workability will also decrease with higher flaky content.
IRJET- Analysis of Compressive Strength of Self Curing Concrete Made using Po...IRJET Journal
This document analyzes the compressive strength of self-curing concrete made using Polyethylene Glycol (PEG400). PEG400 is used as an internal curing compound to prevent moisture loss from concrete and allow for more complete hydration. Tests were conducted on M20 grade concrete with 0-1.5% PEG400 by weight of cement. Results found that 0.5-1% PEG400 concrete had higher 7 and 28-day compressive strengths than plain concrete, with less cracking. PEG400 improved workability and water retention, allowing for better strength development over time compared to traditional curing methods.
IRJET- A Review on Strength Properties of Concrete with Partial Replacement o...IRJET Journal
This document summarizes research on the strength properties of concrete with partial replacement of cement by ground granulated blast furnace slag (GGBS). It first provides background on GGBS, noting that it is a byproduct of iron manufacturing with similar chemical composition to portland cement. The document then reviews literature on the topic, finding that compressive strength of GGBS concrete increased at 40% replacement but decreased with further additions. Experimental results from the study found optimal GGBS replacement is 40% for maximum strength. In conclusion, GGBS can improve concrete strength when used to partially replace cement.
IRJET- Study on Mechanical Propertiesof Polymer ConcreteIRJET Journal
This document summarizes a study on the mechanical properties of polymer concrete. Specifically, it examines how adding different polymers to concrete impacts properties like compressive strength, tensile strength, and workability. Concrete cubes and beams were produced using cement, aggregates, and various polymers like polyvinyl chloride, styrene butadiene rubber latex, polystyrene, and polypropylene. Tests on the samples found that adding 10% styrene butadiene rubber latex increased compressive and tensile strengths the most compared to other polymers and plain concrete. Workability was highest with 15% styrene butadiene rubber latex. The study concludes certain polymers like polyvinyl chloride and styrene butadiene rubber latex can improve
This document discusses a study that evaluated the economic benefits of using an activator material called A-BFS (Activator Blast Furnace Slag) in concrete mixes. The study found that using A-BFS can induce early strength in concrete containing blast furnace slag, potentially allowing construction cycles for reinforced concrete buildings to be reduced from 6-4 days. The study conducted physical property tests on concrete with partial replacement of ordinary Portland cement with A-BFS. It then estimated the potential construction cost savings from shortening construction periods for a sample apartment building project using different A-BFS mix ratios. The study estimated that Cases 3 and 4 could save around 106 million and 160 million Korean won, respectively, through an earlier removal
IRJET- A Review on Applicability of Bacteria in Self-Healing Self-Curing Conc...IRJET Journal
This document reviews the applicability of bacteria as self-healing agents in self-curing concrete. It discusses how various studies have encapsulated bacteria in concrete to induce calcium carbonate precipitation to heal cracks. The document also examines how chemicals like polyetheylene glycol have been used as internal curing agents to improve hydration and strength of self-curing concrete without external curing. The optimal dosages of these agents found in different studies are summarized. The document concludes that incorporating self-healing efficiency through bacterial precipitation and internal curing can significantly reduce maintenance costs for concrete structures.
IRJET-Effect of Mixed Fiber Reinforced Concrete Exposed to Different Exposure...IRJET Journal
This document summarizes a study on the effect of mixed fiber reinforced concrete exposed to different conditions. Cubic concrete specimens containing various combinations of steel and glass fibers were cast and exposed to either water or 5% sulfuric acid solutions. The specimens were tested after 7 and 28 days to evaluate properties like compressive strength, ultrasonic pulse velocity (UPV), and weight loss. The results showed that concrete with a 50% glass fiber and 50% steel fiber mixture performed best in terms of UPV values and compressive strength gain when exposed to both water and acid conditions. Specimens exposed to acid generally showed higher UPV and lower weight loss compared to those cured in water. The study aims to evaluate the durability of fiber
Experimental Investigation of High – Strength Characteristics of Self Curing ...IJMTST Journal
In concrete structures exposed to the ambient air at early ages, the moisture content in concrete
decreases due to moisture diffusion. In addition, self-desiccation due to hydration of cement causes an
additional decrease of moisture content in concrete at early ages, especially for high-strength concrete. In this
study, the internal relative humidity in drying concrete specimens was measured at early ages. Furthermore,
the variation of relative humidity due to self-desiccation in sealed specimen was measured. The moisture
distribution in low-strength concrete with high water/cement ratio was mostly influenced by moisture
diffusion due to drying rather than self-desiccation. In high-strength concrete with low water/cement ratio,
however, self-desiccation had a considerable influence on moisture distribution. The results obtained from
the moisture diffusion theory were in good agreement with experimental results.
IRJET- Crushed Plastic Waste in ConcreteIRJET Journal
This document presents a study on the use of crushed plastic waste as a partial replacement for coarse aggregate in concrete. Several concrete mixes were prepared with 10%, 20%, and 30% replacement of coarse aggregate with crushed plastic waste. The workability and compressive and flexural strengths of the concrete mixes were tested and compared to a control concrete mix without plastic waste. The results showed that concrete with 10% plastic waste replacement achieved a compressive strength similar to the control mix. Compressive and flexural strengths decreased with higher levels of plastic waste replacement but remained acceptable. The study concluded that crushed plastic waste can partially replace coarse aggregate in concrete, particularly at a 10% replacement level, providing a potential use for plastic waste while maintaining good concrete
IRJET- Rice Husk as a Filler Material in High Strength ConcreteIRJET Journal
This document discusses using rice husk ash (RHA) as a filler material in high-strength concrete to improve properties and reduce costs. RHA can replace 5-10% of cement through pozzolanic reactions that improve the cementation matrix and strength. Tests found compressive strengths of 30 MPa after 28 days for concrete with RHA replacements, similar to plain high-strength concrete. Using RHA promotes more sustainable use of agricultural byproducts in construction.
Comparative Analysis of Destructive and Non-Destructive Testing Method of Con...ijtsrd
This work presents a study on the comparison between Destructive Compressive test and Non destructive testing techniques Schmidt Rebound Hammer . Tests moisture content, Sieve analysis, particle density for aggregate and cement paste, bulk density, standard consistency of cement, slump test were performed on both the aggregate and cement to compare their accuracy of both methods and test the quality of the material to be used for concrete casting and estimating the strength of concrete. Seventy samples cubes of 150 x 150 x 150mm were prepared using mix designs of 1 2 4 with a constant w c ratio of 0.45 and were tested at 7, 14, 21 and 28 days respectively. From the results, the rebound number increased from an average of 12 for 7days to an average rebound number of 17.7 for 28days which is similar to the increment in compressive strength from an average of 24.3 for 7days to an average of 32 for 28days which show that the increment in the strength is uniform but 5 difference in value obtained. The slump test was between 62 78mm. From the results of the analysis, it was observed that the strength obtained from destructive process conformed to targeted mix value, whereas that of the Rebound hammer was below these values. Statistical analysis of the results obtained showed that 5 difference exists between the results obtained from the two methods. Hence, there was no significant difference between the means of the two methods for both mixes at a 0.05 level of significance. Non destructive Testing is observed to be more economical as it required no electricity and can also be used directly in the field. Onyeka, F. C | Mama, B. O "Comparative Analysis of Destructive and Non-Destructive Testing Method of Concrete Strength using Compressive and Rebound Harmmer Testing Method" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29389.pdfPaper URL: https://www.ijtsrd.com/engineering/civil-engineering/29389/comparative-analysis-of-destructive-and-non-destructive-testing-method-of-concrete-strength-using-compressive-and-rebound-harmmer-testing-method/onyeka-f-c
Impact of Biomedical Waste on City Environment :Case Study of Pune India.IOSR Journals
Indian cities are facing problem of Biomedical waste management in the wake of urban development. The number of healthcare facilities is increasing day by day resulting in large-scale generation of bio medical waste. It has been observed that inadequate disposal of biomedical waste is creating highly unhygienic environment and posing serious heath threat for inhabitants. Present paper discusses the issue of biomedical waste management from a wider perspective with special emphasis on chemical waste which is one of the most hazardous wastes in present context. Various types of biomedical waste with reference to generation, handling and disposal practices are presented. It includes study and analysis of the parameters which affect the quality of environment to explore their impact on city environments. The current practices of handling such waste is presented based on a study conducted in city of Pune, which is the second largest city in the state of Maharashtra, India. It is aimed to put forth the importance of adequate handling and treatment of biomedical waste with reference to healthy and hygienic living environment for inhabitants to live in.
Outlining Bangla Word Dictionary for Universal Networking LanguageIOSR Journals
This document discusses outlining a Bangla word dictionary for the Universal Networking Language (UNL) system. UNL is an artificial language that allows computers to process information across languages. The authors have been working to include Bangla in the UNL system. They describe the format of a UNL dictionary entry, which includes the headword (Bangla word), universal word, and grammatical attributes. Simply searching the UNL knowledge base for universal words is not effective, so they propose finding universal words based on existing translations of Bangla texts to English and their UNL expressions. The goal is to develop a Bangla dictionary to facilitate converting Bangla sentences to UNL format.
Flash chromatography guided fractionation and antibacterial activity studies ...IOSR Journals
This document summarizes a study that fractionated extracts of Angelica archangelica roots using flash chromatography and tested the fractions for antibacterial activity. Several fractions showed promising antibacterial activity, with minimum inhibitory concentrations ranging from 125-500 μg/ml against four bacterial strains. The most active fractions were from methanol extracts. All ethyl acetate fractions exhibited activity. Further investigation of these fractions could uncover bioactive compounds responsible for the plant's traditional medicinal uses.
Effect of Industrial Bleach Wash and Softening on the Physical, Mechanical an...IOSR Journals
Abstract : Garments washing is a novel process to impart worn-out look, to modify the appearance and to
improve the comfort ability of the garments. Bleach wash is used to fade the color of denim in a higher degree
as well as bleach wash has effect on the physical and mechanical properties of the denim also. This paper
presents the impact of bleach wash and subsequent softening treatment on 100% cotton denim dyed with indigo
dye. Garments were washed using a bleach concentration of 10 g/l for 30 minutes in 50oC temperature and then
softened using standard recipe. The physical, mechanical and color properties were analyzed in before wash,
after desizing, after bleaching and after softening. The properties that were analyzed include hand feel, tensile
strength, seam strength, fabric weight, stiffness, dimensional stability and color fading. Bleach washed and
softened garments exhibit a great difference in the physical, mechanical and color properties than the unwashed garments. Keywords: Denim, Bleach Wash, Garments Washing, Softening
Analysis of failure of Brakes due to leakages of cylinder through CFDIOSR Journals
Today’s world is very fast moving and in this world we all are well understand that the how
important brake is? Effectiveness of braking system are essentials part to avoid accidents and save life. Also
majority of accidents in vehicles are happen due to chassis failure and braking failure. Here I take the subject to
understand the causes of failure of hydraulic brake systems in SUV. The brakes are the most important
active safety of a car and one of its key pieces. However, many drivers do not seem to understand it well.
According to a statistics, about 40% of the defects detected by the ITV correspond to the brakes. It is not enough
to bring the car to the shop when something goes wrong.
Leakage is major problem in TMC. In any case if tmc leak it may leads to accident. So
leakage and performance of tmc is most important. Various parts of tmc such as piston, spring does not leak.
The body of tmc may leak as well seals used in assembly of piston.
In this project the different reasons of leakages are finding and simulation with CFD are carried out
Wireless Sensor Grids Energy Efficiency Enrichment Using Quorum TechniquesIOSR Journals
This document proposes a Quorum-based Medium Access Control (QMAC) protocol to improve energy efficiency in wireless sensor networks. QMAC enables sensor nodes to sleep longer under light traffic loads by only waking up during assigned "quorum time frames". Each node selects one row and column from a grid as its quorum set. This ensures any two nodes' quorums will intersect at some time, allowing communication while keeping individual duty cycles low. Results show QMAC conserves more energy and maintains low latency compared to existing protocols that require nodes to wake up at every time frame regardless of traffic.
High Speed Signed multiplier for Digital Signal Processing ApplicationsIOSR Journals
This document discusses high speed multiplier architectures for digital signal processing applications. It begins by introducing the importance of fast multiplication in DSP algorithms. It then describes the Vedic multiplication algorithm and how it can be implemented for 4-bit and 8-bit numbers using the Urdhva Tiryakbhyam technique. Next, it introduces the Booth encoding technique for radix-8 multiplication and discusses how it reduces the number of partial products. Simulation results are shown comparing the Vedic and radix-8 multiplier architectures. The radix-8 multiplier is concluded to have better performance in terms of power, delay, and power-delay product, making it well-suited for DSP applications.
A Comparative Study on Dyeing of Cotton and Silk Fabric Using Madder as a Nat...IOSR Journals
This document presents a study comparing the dyeing of cotton and silk fabrics with madder, a natural red dye. Various mordanting techniques were tested, including pre-mordanting, post-mordanting, and simultaneous mordanting with alum and copper sulfate. The dyed fabrics were evaluated based on color characteristics and colorfastness properties. The results showed that silk fabrics dyed darker shades than cotton and exhibited better colorfastness to washing and rubbing when mordanted. Mordanted silk samples showed deeper colors and greater wash fastness compared to mordanted cotton samples. While mordanting improved some properties, the dyed fabrics generally displayed poor perspiration fastness.
This document summarizes research on the effect of soil-structure interaction (SSI) on a high-rise reinforced concrete building located in Mumbai, India. SSI considers how a structure's foundation and the underlying soil affect each other when experiencing dynamic loads like earthquakes. The study models a 42-storey building using ETABS and analyzes the structure both with and without considering SSI effects using pile-raft and raft foundations in MIDAS GTX NX. Results show that accounting for SSI leads to reduced settlements, reactions and solid stresses compared to a fixed-base model. The conclusions emphasize that SSI effects are most important for flexible structures on soft soils and that simple analytical models are usually sufficient for engineering applications
Review On Google Android a Mobile PlatformIOSR Journals
This document reviews Google's Android mobile platform. It begins by providing background on the increasing popularity of smartphones and how Android was launched as an open-source platform to compete with other mobile platforms. It then describes the architecture of the Android software stack, including the Linux kernel, runtime environment, and application framework. Finally, it discusses the Android application execution process and how Android improved on the conventional mobile approach by giving all applications equal access to system resources.
Optimization of Threshold Voltage for 65nm PMOS Transistor using Silvaco TCAD...IOSR Journals
This document summarizes research optimizing the threshold voltage (VTH) for a 65nm PMOS transistor using Silvaco TCAD simulation tools. The researchers varied three fabrication factors - gate oxide thickness, channel doping concentration, and channel implantation concentration - in the simulation. The simulation results showed a VTH value of -2.55427V for a 65nm PMOS transistor with a gate oxide thickness of 0.0025um, boron channel doping of 2x1015, and phosphorus implantation of 3.5x1013 atom/cm-1. Thicker gate oxides, higher channel doping, and increased implantation concentrations each caused higher VTH values in the simulation, consistent with theoretical expectations.
Review: Semi-Supervised Learning Methods for Word Sense DisambiguationIOSR Journals
This document provides a review of semi-supervised learning methods for word sense disambiguation. It discusses how semi-supervised learning uses both labeled and unlabeled data, requiring only a small amount of labeled data. The document outlines several semi-supervised learning techniques for word sense disambiguation, including bootstrapping algorithms like Yarowsky's algorithm, and graph-based approaches like label propagation. It provides details on Yarowsky's bootstrapping algorithm and how it is able to generalize to label new examples through exploiting properties like one-sense-per-collocation and language redundancy.
Automated Surveillance System and Data CommunicationIOSR Journals
This document summarizes an automated video surveillance system that uses fuzzy color histograms (FCH) for background subtraction. It begins with an introduction to automated video surveillance and challenges with background subtraction. It then describes how the system works, including:
1) Calculating FCH features for each pixel using fuzzy membership values to color bins, which allows robustness to noise and quantization errors.
2) Comparing FCH features between current and background model frames using a similarity measure to classify each pixel as background or foreground.
3) Adaptively updating the background model at each pixel position over time using an online learning approach.
The key advantage of this approach is that the fuzzy color histograms allow efficient attenuation of
An Efficient Algorithm for the Segmentation of Astronomical ImagesIOSR Journals
This document proposes an efficient algorithm for segmenting celestial objects from astronomical images. The algorithm uses multiple preprocessing steps including removing bright point sources, stationary wavelet transform, total variation denoising, and adaptive histogram equalization. Level set segmentation is then used as the key technique for segmentation. Preprocessing helps overcome issues like noise, weak object edges, and low contrast. Level set segmentation can segment objects while retaining their texture and shape information for subsequent classification. The algorithm is tested on various celestial objects and shown to effectively segment them.
- The document experimentally investigates and optimizes welding parameters for TIG welding of 7005 aluminium alloy. TIG welding was used to weld 5mm thick 7005 aluminium alloy plates while varying the welding parameters.
- Welding current, gas flow rate, welding speed, and electrode gap were selected as input parameters to study their effect on the tensile strength and hardness of the welded joints, which were selected as output responses.
- An L9 orthogonal array based on Taguchi methods was used to design the welding experiments. The experiments analyzed the effect of parameters on tensile strength and hardness using signal-to-noise ratios. Welding current was found to have the greatest influence on tensile
1. The document analyzes the nutritional composition, physicochemical properties, and short-term toxicological effects of beniseed (Sesanum indicum) oil in albino rats.
2. The beniseed was found to contain moderate levels of protein, fat, and carbohydrates, making it a good source of nutrients. Its oil had properties suggesting potential industrial and dietary uses.
3. Rats fed a diet with 5% beniseed oil showed increased weight gain and feed consumption compared to controls, with no significant differences in organ weights or blood parameters, indicating no apparent toxic effects of short-term consumption.
The document proposes a new security method called Yours Advanced Security Hood (YASH) to prevent password cracking through brute force and dictionary attacks. YASH uses a two-level security approach:
1. It tracks the number of incorrect login attempts and activates a virtual machine crosschecking (VMC) process if the attempt threshold is exceeded, preventing the password from being matched to attempted passwords.
2. It allows the true user to initiate an unauthorised access control (UAC) using their mobile phone to signal that no attempts should be matched, protecting the account until the user deactivates UAC.
3. The system can then detect the true user by their ability to deactivate UAC through their
Early Warning on Disastrous Weather through Cell PhoneIOSR Journals
1) The document proposes an early weather warning system for Bangladesh that alerts subscribers via phone calls or SMS about impending natural disasters like cyclones, tsunamis, or tornadoes.
2) The system collects weather data from various sources and sends warning messages to subscribers based on their detected location. Warnings are sent via automated phone calls in Bengali to ensure all subscribers can understand, even if asleep.
3) Testing showed the system works well within Dhaka, with fast response times due to storing processed data. The system aims to minimize loss of life from natural disasters by providing widespread early warnings to the Bangladeshi population.
This document summarizes an experiment on enhancing the heat transfer efficiency of a counter flow heat exchanger by using API SN oil and Super Kool Xtra oil. The experimental setup uses a copper tube heat exchanger with the hot fluid passing through the inside of the copper tube and the cold fluid passing over the outside. Temperature readings are taken at the inlet and outlet of both fluids. The results show that API SN oil provides greater heat transfer efficiency than water or Super Kool Xtra oil based on the temperature changes of the fluids. The heat exchanger has applications in industries involving heat transfer like oil/gas, power generation, and industrial processing.
This document analyzes the stress on helical coil springs made of different materials that are used in two-wheeler vehicles. It discusses the modeling of a spring in CATIA software and analyzing it in ANSYS. Four materials are considered - structural steel, aluminum alloy, titanium alloy, and chrome vanadium. The maximum shear stress and total deformation of each material under load are calculated and chrome vanadium is found to have the lowest stress and deformation, making it the best material out of the four considered for springs.
The Research on Process and Application of Self-Compacting ConcreteIJERA Editor
Self-compacting concrete (SCC) is one kind of concrete with high workability and durability. First of all, this paper introduces the definition and history of Self-compacting concrete (SCC). Secondly, it introduces the raw material selection, equipped technology and the mix proportion design method of Self-compacting concrete. Finally, it analyzes the problems and countermeasures of self-compacting concrete and look ahead the application prospect of it.
This document discusses research into producing high-strength concrete with a compressive strength of 80 MPa using locally available materials in Sudan. It describes two statistical approaches to developing optimized concrete mix designs: the ACI 211.4 method and using JMP statistical software. Hundreds of concrete specimens were tested with local Sudanese aggregates, silica fume, fly ash, and superplasticizers at different ages and water-cement ratios. Thirty-three high-strength concrete mix designs were successfully developed and evaluated. The results provide guidance on optimizing mix properties and demonstrate that local materials can be used to produce high-strength concrete in Sudan.
IRJET - Durability of Concrete with Differential Concrete Mix DesignIRJET Journal
The document discusses the durability of concrete with different concrete mix designs. It presents research on how water absorption, density, and sorptivity coefficient are affected by varying the water-cement ratio, slump, and compressive strength in concrete mixes. Seventy-two concrete cubes were prepared with six different mix designs - three mixes varied the slump and water-cement ratio at a constant compressive strength, while three other mixes varied the compressive strength and water-cement ratio at a constant slump. The cubes were tested to determine their rate of water absorption, density, and sorptivity coefficient at various time intervals over 28 days. The results showed that the sorptivity coefficient and rate of water absorption
This document summarizes research on crumb rubber concrete blocks. The research aims to address challenges in producing concrete with crumb rubber from tires and to improve its properties. Concrete mixes with 5%, 7.5%, and 10% crumb rubber were tested at 7 and 28 days. Compressive and tensile strengths were initially lower than conventional concrete but increased with the addition of silica fume. The document concludes that crumb rubber concrete blocks with 5% rubber and silica fume can be used in colder regions due to increased durability, abrasion resistance, and reduced impacts of freezing and thawing. The research helps advance the use of waste tire rubber in concrete applications.
Quality control of concrete and its importanceARUNKUMARC39
Quality control of concrete is important for structural integrity, durability, strength, and regulatory compliance. It involves testing materials, establishing mix designs, monitoring batching and mixing, sampling fresh concrete, and testing compressive strength. Quality control is applied at different stages of construction through measures like material testing, mix design adherence, sampling, curing monitoring, and documentation. This helps deliver concrete that meets specifications and performs as intended.
IRJET- Comparision between Destructive and Non-Destructive Test on ConcreteIRJET Journal
This document compares destructive and non-destructive testing techniques for concrete, specifically rebound hammer testing and ultrasonic pulse velocity testing. Twenty-seven concrete cube samples were tested destructively via compression testing at 7, 14, and 28 days to determine compressive strength. The samples were also tested non-destructively using a rebound hammer and ultrasonic pulse velocity method. A higher correlation was found between rebound hammer readings and compressive strength than between ultrasonic pulse velocity and compressive strength. The rebound hammer provided correlation coefficients of 1.63, 2.25, and 2.52 at 7, 14, and 28 days respectively, while ultrasonic pulse velocity provided coefficients of 1.11, 1.05
This document discusses quality control of ready mixed concrete. Ready mixed concrete has better quality than site mixed concrete due to sophisticated batching equipment and quality control testing of materials. Materials like cement, aggregates, fly ash, slag and admixtures are tested according to Indian standards to ensure quality. Properties of fresh concrete like workability and cohesiveness are also controlled. Maintaining quality is important as ready mixed concrete is widely used in construction for its consistency, speed of construction, and reduced waste.
Influence of Diverse Aggregates on Concrete CharacteristicsIRJET Journal
This document discusses how different types of aggregates influence the characteristics of concrete. It reviews several studies that examined how aggregate shape, size, texture, and material affect the strength and workability of concrete. Angular aggregates are generally found to produce stronger, more workable concrete than rounded aggregates due to their larger surface area and better interlocking. The document also explores the use of industrial byproducts like marble powder and steel slag as alternative materials in concrete production in order to improve sustainability.
IRJET- Quality Control of Concrete through Accelerated CuringIRJET Journal
This document discusses a study on using accelerated curing to improve quality control of concrete. Accelerated curing involves elevated curing temperatures to increase the rate of strength gain in concrete. The study aims to investigate the reliability of using a single correlation equation to predict 28-day concrete strengths when minor changes are made to mix proportions. Specifically, it analyzes how well a single correlation performs for concrete mixes with water-cement ratios of 0.60, 0.50, and 0.35 when cement or water content are varied by up to 1% based on code-allowed tolerances. It also compares results to correlations provided in the Indian standard IS 9013 for warm water curing. The results can help concrete producers determine
IRJET- To Study the Effect of Recycled Aggregate in High Strength ConcreteIRJET Journal
This study evaluated the effect of replacing natural coarse aggregates with recycled concrete aggregates at different replacement percentages (0%, 25%, 50%, 60%, 70%, 80%, 90%, 100%) on the compressive and flexural strengths of concrete. The results showed that compressive and flexural strengths decreased as the replacement percentage increased, except at 60% replacement where the strengths were similar to the control concrete (0% replacement). The maximum recommended replacement percentage was determined to be 60%, beyond which strengths started to significantly decrease. Replacement of up to 60% recycled concrete aggregates was found to produce concrete with comparable strengths to conventional concrete.
This document summarizes a project report on strengthening concrete blocks with the addition of rubber scrap and coconut shells. The report describes testing concrete blocks containing 5% rubber scrap replacing coarse aggregate. Fly ash was also added, varying from 0-20% replacing cement. The project aimed to reuse rubber waste and study the properties of rubberized concrete blocks. Testing found rubberized concrete more durable but weaker, with lower strength than ordinary concrete. Adding silica increased strength. Properties of concrete with 10-20% coarse aggregate replaced with coconut shells were also studied. Results showed lower strength but higher absorption in coconut shell concrete compared to normal concrete. The addition of fly ash and steel fibers improved mechanical properties. This study explored using waste materials like rubber and
This document summarizes an assessment of strengthening work done on a residential building in Aurangabad, Maharashtra, India. Non-destructive testing was conducted before and after strengthening to evaluate the building's condition. Testing found some columns to be weak. Strengthening recommendations included grouting columns with micro fine cement and epoxy resin, as well as applying micro concrete jacketing to weak columns. Post-strengthening testing saw improvements but some columns still needed strengthening. The work aimed to repair deficiencies and retrofit the structure to protect lives and extend its structural life.
IRJET- Use of Brick Dust and Fly Ash as a Replacement of Fine Aggregates in S...IRJET Journal
This document discusses a study on the use of brick dust and fly ash as replacements for fine aggregates in self-compacting concrete. It provides background on self-compacting concrete and its advantages over normal vibrated concrete. The study aims to compare the mechanical properties of self-compacting concrete and normal concrete with various ratios of fly ash and brick dust replacing fine aggregate. A literature review covers research on the effects of paste content and powder-to-water ratio on the properties of self-compacting concrete, as well as using fly ash and brick dust as additions in concrete mixes.
A Review of Effective Use of Fischer Chemical for Rebaring in Existing Concre...IRJET Journal
The document summarizes research on the effective use of Fischer Chemical for rebaring in existing concrete structures. It begins with an abstract that outlines the research goals of comparing the strength of conventional concrete cubes to cubes cast with Fischer Chemical adhesive after drilling holes and inserting rebar. It then provides background on rebaring techniques and the benefits of using chemical adhesives. The literature review summarizes previous research finding that pullout strength is higher for samples with higher reinforcement ratios and stronger concrete. The study aims to determine the resistance value of Fischer Chemical through pullout and splitting tensile tests on control cubes and cubes cast with drilled holes and rebar.
This document summarizes an experimental study on developing ultra-high strength self-compacting concrete with a target compressive strength of M160 grade (approximately 160 MPa). Three mix designs were tested with cement contents ranging from 450-600 kg/m3. The mixes used GGBS to replace 40% of the cement and included silica fume, polycarboxylate ether admixture, and steel or polymer fibers. The fresh properties of self-compactability, passing ability, and resistance to segregation were evaluated using slump flow, L-box, V-funnel, and U-box tests. The hardened properties of compressive and flexural strength were determined on cube, cylinder, and beam
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4. Organizational processes and structures that may inhibit effective AI adoption.
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1. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 13, Issue 3 Ver. III (May- Jun. 2016), PP 89-98
www.iosrjournals.org
DOI: 10.9790/1684-1303038998 www.iosrjournals.org 89 | Page
A Study on the Quality Control of Concrete Production in Dhaka
City
Md. Ashraful Alam1
, Md. Zakaria Habib2
, Md. Raihan Sheikh3
,Abu Hasan4
1, 2
(Lecturer, Department of Civil & Environmental Engineering, Uttara University, Bangladesh)
3, 4
(Department of Civil Engineering, Dhaka University of Engineering & Technology, Bangladesh)
Abstract: The quality control of concrete is the most important issue in achieving its desired strength and
durability.The principal aim of the study was to investigate the existing practices on the quality control of
concrete production in Dhaka city. In doing so the key factors involved quality control of concrete production
were identified. Various questions on the factors that affect quality control of concrete production were
prepared for the purpose of this study. A total of forty five construction sites were visited at different location in
Dhaka city and relevant data were collected. During the survey the necessary information was collected by eye
observation, asking question to the site engineer and from written documents kept in the site. The survey results
have shown that in Dhaka city most of the concrete production companies are neither aware of the key factors
nor following the quality control of concrete. Eventually, an inferior quality of concrete is being achieved in
Dhaka city which can affect both the strength and the durability of the most of structures those are being
constructed currently.
Keywords: Concrete, Strength, Aggregate, Quality Control and Durability
I. Introduction
Concrete is a major component of most of our infrastructural facilities today in the 21st century
because of its versatility in use. Concrete is used more than any other man-made material in the world [1-
6].Concrete is generally produced in batches at the site with the locally available materials of variable
characteristics. It is, therefore, likely to be variable from one batch to another. The magnitude of this variation
depends upon several factors, such as (a) variation in the quality of constituent materials; (b) variation in mix
proportions due to batching process; (c) variation in the quality of batching and mixing equipment available; (d)
the quality of overall workmanship and (e) supervision at the site [1-3]. Moreover, concrete undergoes a number
of operations, such as transportation, placing, compacting and curing [1]. During these operations considerable
variations occur partly due to quality of plant available and partly due to differences in the efficiency of
techniques used. Thus there are no unique attributes to define the quality of concrete entirely. Under such a
situation concrete is generally referred to as being of good, fair or poor quality. This interpretation is subjective.
It is, therefore, necessary to define the quality in terms of desired performance characteristics, economics,
aesthetics, safety and other factors. Due to the large number of variables influencing the performance of
concrete, quality control is an involved task.
Therefore, the aim of quality control is to reduce the above variations and produce uniform material
providing the characteristics desirable for the job envisaged. Thus quality control is a corporate, dynamic
program to assure that all aspects of materials, equipment and workmanship arc well looked after. The tasks and
goals in these areas are properly set and defined in the specifications and control requirements. The
specifications have to state clearly and explicitly the steps and requirements, adherence to which would result in
a construction of acceptable quality. Except for compressive strength and appearance there is no early measure
of construction performance. Each step in construction procedure is therefore to be specified. The probability
based specifications containing allowable tolerances on its attributes is more rational and is preferred. Quality
control is thus conformity to the specifications, not more not less. The most practical method of effective quality
control is to check what is done in totality to conform to the specifications. An owner will have no right to
expect anything more than what is in the specifications. The builder, on the other hand, knows that anything less
than what is in the specifications will not be acceptable to the owner. The main objective of the study is to
evaluate the present practices for the quality control of concrete production in Dhaka city.
1.1 Methodology
The working methodology of the study was followed as given below:
(i) Identification of key factors involved quality control of concrete production.
(ii) Preparation of various questions on the factors that affect quality control of concrete production.
(iii) Collection of data from under construction project in Dhaka city on the quality control of concrete
production.
2. A Study on the Quality Control of Concrete Production in Dhaka City
DOI: 10.9790/1684-1303038998 www.iosrjournals.org 90 | Page
(iv) Analyzing field data.
(v) Conclusion on the analysis and necessary recommendation.
1.2 Scope of the study
This study was focused on examining the existing practices for quality control of concrete at project
sites in Dhaka city. The reason behind choosing concrete is its greatest significance to be used in a structural
member.
II. QUALITY OF CONCRETE
Quality means excellence. It is thus a philosophy rather than a mere feature. The difference between
two objects is judged by their qualities. We set some standards those can determine the level of acceptability. In
most industries especially in manufacturing and processing, the concept of quality control is old and used
extensively.
Nowadays, application of quality control is not only becoming popular but also mandatory in
construction industry. Just knowing some quality control methods or procedures will not do any good. We must
have to adopt and implement the quality control methods and tools that are available to us. The concept and its
practice must be tuned in harmoniously. Quality control in construction activities guides the implementation of
correct structural design, specifications and proper materials ensuring that the quality of workmanship by the
contractor /sub-contractor is achieved.
2.1 Factors affecting in the quality of concrete
In view of the different processes involved in the manufacture of concrete, the problems of quality
control are diversified and their solution elaborated. The factors involved are the personnel, the materials and
equipment, the workmanship in all stages of concreting, i.e. batching of materials, mixing, transportation,
placing, compaction, curing, and finally testing and inspection. It is therefore necessary to analyze the different
factors causing variations in the quality and the manner in which they can be controlled.
2.1.1 Materials
For a uniform quality of concrete, the ingredients (particularly the cement) shall preferably be used
from a single source. When ingredients from different sources are used, the strength and other characteristics of
the materials are likely to change and, therefore, they should only be used after proper evaluation and testing.
2.1.1.1 Cement
Cement is any material that hardens and becomes strong adhesive after application in plastic form.
Cement is the binding constituent of concrete. Similar types of cement from different sources and at different
times from the same source exhibit variations in properties of concrete, especially in compressive strength. This
variation in the strength of cement is related to the composition of raw materials as well as variations in the
manufacturing process. The cement shall be tested initially once from each source of supply and, subsequently,
at every two months interval. Adequate storage under cover is necessary for protection from moisture. Set
cement with hard lumps is to be rejected.
2.1.1.2 Aggregates
In any concrete, aggregates (fine sand and Coarse) usually occupies about 70-75% and between 60 –
80% of the total volume of the concrete mass. The aggregates have to be graded so the whole mass of concrete
acts as a relatively solid, homogeneous, dense combination with the smallest particles acting as inert filler for
the voids that exist between the larger particles. This therefore suggests that the selection and proportioning of
aggregates shall be given due attention as it not only affects the strength, but the durability and structural
performance of the concrete also. Further, the aggregate is cheaper than cement and thus it is cheaper to use as
much quantity of aggregate and as little of cement as possible. Aggregates provide better strength, stability and
durability to the structure made out of cement concrete than cement paste alone. Aggregate is not truly inert
because its physical, thermal and chemical properties influence the performance of concrete. While selecting
aggregate for a particular concrete, the economy of the mixture, the strength of the hardened mass and durability
of the structure must first be considered. Grading, maximum size, shape, and moisture content of the aggregate
are the major source of variability. Aggregate shall be separately stock piled in single sizes. The graded
aggregate should not be allowed to segregate.
3. A Study on the Quality Control of Concrete Production in Dhaka City
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2.1.1.3 Water
The water used for mixing concrete shall be free from silt, organic matter, alkali, and suspended
impurities. Sulphates and chlorides in water should not exceed the permissible limits. Generally, water fit for
drinking may be used for mixing concrete.
2.1.2 Personnel
The basic requirement for the success of any quality control plan is the availability of experienced,
knowledgeable and trained personnel at all levels. The designer and the specification-writer should have the
knowledge of construction operations as well. The site engineer shall be able to comprehend the specification
stipulation .Everything in quality control cannot be codified or specified and much depends upon the attitude
and orientation of people involved. In fact, quality must be a discipline imbibed in the mind and there shall be
strong motivation to do everything right the first time.
2.1.3 Equipment
The equipment used for batching, mixing and vibration shall be of the right capacity. Weigh-batchers
shall be frequently checked for their accuracy.
2.1.4 Workmanship
The activities involved in the workmanship in all stages of concreting, i.e. batching of materials, mixing,
transportation, placing, compaction, curing and finally testing and inspection.
2.1.4.1 Ready mixed concrete
If instead of being batched and mixed on site, concrete is delivered for placing from a central plant, it is
referred to as ready-mixed or pre-mixed concrete. This is used for large batches with lorry transporters up to
6m3
capacity. It has the advantage of eliminating site storage of materials and mixing plant, with the guarantee
of concrete manufactured to quality-controlled standards. Placement is usually direct from the lorry therefore
site-handling facilities must be co-ordinate with deliveries.
Advantages of Ready-Mix Concrete:
(a) Close quality control of batching which reduces the variability of the desired properties of the hardened
concrete.
(b) Use on congested sites or in highway construction where there is little space for a mixing plant and
aggregate stockpiles.
(c) Use of agitator trucks to ensure care in transportation, thus preventing segregation and maintaining
workability
(d) Convenience when small quantity of concrete or intermittent placing is required.
The disadvantage of ready-mix concrete is that it is costlier by about 10 – 15% than concrete mixed at
project site. But this is often off-set by savings in site organization, in supervisory staff, and in cement content.
2.1.4.2 Concrete mix ratio
When making concrete it's important to use the correct concrete mixing ratios to produce a strong,
durable concrete mix. Mixing water with the cement, sand, and stone will form a paste that will bind the
materials together until the mix hardens. The strength properties of the concrete are inversely proportional to the
water/cement ratio. Basically this means the more water you use to mix the concrete (very fluid) the weaker the
concrete mix. The less water you use to mix the concrete (somewhat dry but workable) the stronger the concrete
mix. Accurate concrete mixing ratios can be achieved by measuring the dry materials using buckets or some
other kind of measuring device. By measuring the mixing ratios you will have a consistent concrete mix
throughout your entire project.
2.1.4.3 Batching of concrete
The correct measurement of the various materials used in the concrete mix is called batching. Errors in
batching are partly responsible for the variation in the quality of concrete.
Concrete can be batched in two ways: -
(I) By Volume batching and
(II) By Mass (weight) batching.
Weigh-batching of materials is always preferred than volume batching. When weigh-batching is not
possible and the aggregates are batched by volume, such volume measures to be regularly checked for the
weight-volume ratio.
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2.1.4.4 Mixing of concrete
This is the practical means of producing fresh concrete and placing it in the form so that it can harden
into the structural or building material referred to as concrete‘. The sequence of operation is that the correct
quantities of cement, aggregates and water, possibly also admixture are batched and mixed in a concrete mixer
which produces fresh concrete. This is transported from the mixer to its final location. The fresh concrete is then
placed in the forms, and compacted so as to achieve a dense mass which is allowed and helped, to harden. The
objective of mixing of concrete is to coat the surface of all aggregate particles with cement paste and to blend all
ingredients of concrete into a uniform mass. Mixing of concrete is done either by hand or by machine.
Mixers performances shall be checked for conformity to the requirements of the relevant standards. Concrete
shall be mixed for the required time; both under-mixing and over-mixing shall be avoided.
2.1.4.5 Transportation
After mixing, concrete shall be transported and placed at site as quickly as possible without
segregation, drying, etc. as soon as concrete is discharged from the mixer, internal as well as external forces
starts acting to separate the dissimilar constituents. If over-weight concrete is confined in restricting forms, the
coarser and heavier particles tend to settle and finer and lighter materials tend to rise. If concrete is to be
transported for some distance over rough ground the runs shall be kept as short as possible since vibrations of
this nature can cause segregation of the materials in the mix. For the same reason concrete should not be
dropped from a height of more than 1m. If this is unavoidable a chute shall be used.
The green concrete shall be handled, transported and placed in such a manner that it does not get segregated.
The time interval between mixing and placing the concrete shall be reduced to the minimum possible.
2.1.4.5 Placing
The formwork and position of reinforcement shall be checked before placing concrete to make sure that
they are clean and free of any detritus, such as ends of tying wire. The fresh concrete shall be deposited as close
as possible to its ultimate position. Care need to be taken when discharging concrete from skips to avoid
dislodging the reinforcement or over filling the formwork. When filling columns and walls, care shall be taken
that the concrete does not strike the face of the formwork, which might affect the surface finish of the hardened
concrete. For deep sections the concrete shall be placed in uniform layers, typically not more than about 500
mm thick, each layer being fully compacted.
2.1.4.6 Compaction
Compaction of concrete is the process adopted for expelling the entrapped air form the concrete. In the
process of placing and mixing of concrete, air is likely to get entrapped in the concrete. If this air is not
detrained out fully, the concrete losses strength considerably.
Anticipated targets of strength, impermeability and durability of concrete can be achieved only by thorough and
adequate compaction. One per cent of the air voids left in concrete due to incomplete compaction can lower the
compressive strength by nearly five percent (Gambhir, 2004).
2.1.4.7 Curing
Curing of concrete is the process of maintaining satisfactory moisture content and a favorable
temperature in concrete during the period immediately after the placement of concrete so that hydration of
cement may continue till the desired properties are developed sufficiently to meet the requirements of service.
The reasons for curing concrete are to keep the concrete saturated or as nearly saturated as possible, until the
originally water filled space in the fresh cement paste has been filled to the desired extent by the product of
hydration of cement, to prevent the loss of water by evaporation and to maintain the process of hydration, to
reduce the shrinkage of concrete and to preserve the properties of concrete.
Adequate curing is essential for the handling and development of strength of concrete. The curing
period depends upon the shape and size of member, ambient temperature and humidity conditions, type of
cement, and the mix proportions. Nevertheless, the first week or ten days arc the most critical, as any drying out
during this young age can cause irreparable loss in the quality of concrete. Generally, the long-term compressive
strength of concrete moist cured for only 3 days or 7 days will be about 60 per cent and 80 per cent,
respectively, of the one moist cured for 28 days or more (Gambhir, 2004).
2.1.5 Formwork
Formwork is a structure, usually temporary, used to contain poured concrete and to mould it to the
required dimensions and support until it is able to support itself. It consists primarily of the face contact material
and the bearers that directly support the face contact material. Proper removal of formwork is an important
factor to achieve good quality of concrete during the service life.
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2.1.6 Inspection & testing
Inspection and testing play a vital role in the overall quality control process. Inspection could be of two
types, quality control inspection and acceptance inspection. For repeated operations early inspection is vital, and
once the plant has stabilized, occasional checks may be sufficient to ensure continued satisfactory results. The
operations which are not of repetitive type would require, on the other hand, more constant scrutiny.
Apart from the tests on concrete materials, concrete can be tested both in the fresh and hardened states. The tests
on fresh concrete offer some opportunity for necessary corrective actions to be taken before it is finally placed.
These include tests on workability, unit weight or air content (if air-entrained concrete is used), etc.
III. Field Survey
The study aims to notice the existing practices which are used to quality control of concrete production
in Dhaka city on project sites. A questionnaire is developed and accordingly data is collected from different
project sites in Dhaka city. In the current case Uttara, Badda, Banani, Mirpur, Mohakhali, Bosuundhora,
Dhanmondi, Kalabagan, Pallabi, Tejgaon, Banasree, Khilkhet and Puran Dhaka regionsare selected.A total
number of forty five (45) on- going construction project sites producing concrete were surveyed and relevant
data were collected according to questionnaire. The building projects were 6 to 10 storied in addition basement.
3.1 Survey techniques
The study was carried out by either physical observation or questioning the site engineer of the
processes involved in the production of concrete from project sites along with some written documents. Site
operations is observed by including the methods employed by site concrete workers at project sites in batching
and mixing of concrete, handling of the concrete, placing, compaction, finishing and curing. Other
investigations have been conducted on project sites were the inspection of cement stores and their storage
system, a check on sections where concrete raw materials are deposited before utilization i.e. where aggregates
are stockpiled, formwork, the nature and sources of water being used for the works as well as the level of
supervision and workmanship.
IV. Results
Quality of concrete depends on the constituent materials, their proportions, mixing, transporting,
placing, compaction and curing of concrete. The concrete with proper mix proportion has the needed
workability and develops the targeted compressive strength. Efficient concrete mixers are needed to mix the
ingredients and to produce a cohesive and workable concrete. Once the concrete is placed and consolidated by
compaction in the formwork, protected and cured properly, it shall be a good quality concrete and is expected to
perform satisfactorily in the service life. Forty five (45) sites are visited to collect relevant information in this
study. The findings of the field investigation works on the quality control of concrete production in Dhaka city
are presented in the coming sections.
4.1 Result and analysis
The survey results have been presented in table and discussed under different parameters. The
parameters are materials, personnel, equipment, workmanship and formwork.
4.1.1 Materials
The main ingredients of concrete are cement, fine aggregate, coarse aggregate and water. The results
were obtained from the sites for all the ingredients are given below:
Survey result of cement is given in Table 1.
Table 1: Survey result of cement
From the above table it is evident that no construction company or building owner has been tested their
cement, even some cases it is found that they did not store properly. Storing of cement at field is presented in
Fig. 1.
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Figure 1: Typical storing of cement at site.
There are mainly two types of sand available in Dhaka city to produce concrete. It is found that 64% of
the total has been using Sylhet sand, 7% using local sand and the rest percent using a mix of local and Sylhet
sand. However, none has been found conducting any laboratory test for fine aggregate. It is seen that in 82%
cases screening has not been conducting and 97% cases washing before use in concreting is ignored. Survey
result of fine aggregate is presented in Table 2. Fig. 2 represents the on field storing of fine aggregate.
Table 2: Survey result of fine aggregate
(a) Sylhet sand (b) Local sand
Figure 2: Typical storing of fine aggregate at site
It has been found that most company used stone chips as coarse aggregate. However, similar practice
has been noticed than the earlier materials, i.e. no laboratory test is being conducted. Moreover, the practice for
storage is improper. Typical on field storing of coarse aggregate is shown in Fig. 3. Survey result of coarse
aggregate is presented in Table 3.
Table 3: Survey result of coarse aggregate
* Few members were cast with stone chips and few members were cast with brick chips.
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(a) Stone chips (b) Brick chips
Figure 3: Typical storing of coarse aggregate at site
WASA supply water is being used in all construction projects in the survey area. But they no test has
been done for water. It is to mention that a few construction project sites used rain water which fell during
construction work illustrated in the figure 4. Survey result of water is presented in Table 4.
Table 4: Survey result of water
`
Figure 4: Water used for concreting
4.1.2 Personnel
From the survey it is found that no supervisor from land owner, no technician and even most cases the
labor have been non-skilled for concreting works. During the survey period the skill of labor was observed by
the sincerity of works, the techniques adopted by themselves for concrete work and their works. Survey result of
personnel is presented in Table 5.
Table 5: Survey result of personnel
4.1.3 Equipment
For quality control of concrete production, the equipment is being used for batching; mixing and
compaction shall be of the right capacity. Survey results were conducted on equipment is given in Table 6.
Table 6: Survey results of equipments used in concreting
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4.1.4 Workmanship
A mixed concrete of ready mix and on site produced concrete has been used in 60% of the study sites,
where on site concrete production is studied in 40% cases. They were mainly used ready mixed for slab and
beam, in situ concrete for column. The batching procedure was found commonly volume batching. But an
important factor w/c ratio was maintained by the experience of mixer. Curing process of the cast concrete has
also been studied where about 80% is found improper. Survey result of workmanship is given in Table 7.
Table 7: Survey result of workmanship
It is seen that ready mix concrete has been extensively used to cast slab and beam. However, the way of
placing and handling of fresh concrete is completely erroneous as shown in Fig. 5.
Figure 5: Slab casting by ready mixed concrete
The quality of in situ concrete was studied during the survey period and the workmanship included in
casting column, beam and even slab were observed. The workmanship of in situ concrete is given in Fig. 6.
Figure 6: Slab casting by in situ concrete
The provisions of final testing differ from company to company which is given in Table 7. The
specimen was kept for testing mainly cylinder is given in Fig. 7.
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Figure 7: Specimen for testing
4.1.5 Formwork
Steel and wooden formwork has been found in the survey project sites as shown in Fig. 8. It is
observed that there had no options in each of project that could make the formwork water tight. Removal of the
formwork has been done in an improper manner.
Table 8: Survey result of formwork
(a) Wooden Formwork (b) Steel formwork
Figure 8: Typical formwork used at site
V. Conclusion
This study gives understanding of the existing practices for quality control of concrete production in
Dhaka city. From the limited scope of present study the following conclusion can be drawn.
(i) No test report for any of the construction materials has been found at any of the project sites visited. Even
the construction materials were not stored properly at the project site.
(ii) Few structural design-drawings have been found as designed by Diploma Engineer. Even some of the
projects have no site engineer. In most of the projects there is no supervisor from land owner and no
concrete technician. Few of the projects were found to have unskilled labor for concreting.
(iii) Almost all of the construction sites maintain their concrete mix ratio by volume batching. The water-cement
ratio is maintained from the practical experience of the person concerned. Besides, in most of the projects
proper curing of concrete is not followed.
(iv) In most of the project no care is taken for water proofing the formworks for concreting. And early removal
of formwork especially those of columns have been found in most of the projects.
VI. Recommendation
The study therefore recommended that:
(i) Concrete Designers/Engineers should specify the concrete materials i.e. water quality, aggregates (grading,
shape, maximum size and absorption capacity). In addition important test of cement that is necessary for
concrete works.
(ii) The utilization of qualified and experienced personnel right at the top management level to the site
manager, supervisors, machine operator, skilled and semi-skilled workers.
(iii) Construction companies should follow relevant standard rules and regulations for concrete works.
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(iv) Government at all levels including private sector operators should urgently enforce the implementation
of the provisions of the National Building Code (BNBC).
Acknowledgements
The authors would like to acknowledge Professor Dr. Mohammad Abdur Rashid, Department of Civil
Engineering, Dhaka University of Engineering & Technology, Gazipur for his kind suggestion and guidance in
conducting this study.
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